Dilation balloon having a valved opening and related catheters and methods

ABSTRACT

Dilation catheters including a mechanism used in, for example, removing gas or air from the catheters are disclosed. A dilation catheter may include an elongated tubular member having a distal end and a proximal end, a proximal handle proximate the proximal end of the tubular member, and an inflatable balloon proximate the distal end of the tubular member with inflatable balloon being in fluid communication with a fluid port to supply inflation liquid to the inflatable balloon. The inflatable balloon may include an opening for permitting gas to exit the inflatable balloon. In the proximate location of the opening, an expandable material or a barrier material that permits gas to exit through the opening, while retaining inflation liquid in the inflatable balloon.

FIELD OF THE INVENTION

This invention relates to dilation catheters and related methodsthereof. In a particular embodiment, the invention relates to methodsand apparatuses for removing air from a balloon dilation catheter priorto insertion of the catheter into a patient's body.

DESCRIPTION OF THE RELATED ART

Balloon dilation catheters have a number of different medicalapplications, such as, for example, deployment of medical stents anddilation of restricted body lumens. Currently, a wide variety of balloondilation catheters are being used, the functions and operationalcharacteristics of which are primarily dependent upon the type ofmedical procedure being performed.

For example, during an intravascular medical procedure, such as, forexample, an angioplasty procedure, a balloon dilation catheter may beused to eliminate or reduce a narrowing in an artery by placing aninflatable balloon in the location of narrowing and inflating theballoon to enlarge the narrowing of the artery. Prior to the catheterinsertion into the body, however, the catheter may require a preppingprocedure to remove all of the air trapped inside the catheter. This isbecause the air (e.g., in the form of air bubbles) trapped in thecatheter may raise a number of safety and operational issues. Inparticular, if the trapped air leaks into a blood vessel by, forexample, balloon rupture or sealing failure, the leaked air, beingcompressible, may expand rapidly, causing obstruction of blood flow(known as air emboli) and causing a serious harm to the patient. Inaddition, the air trapped inside the balloon and a fluid lumen used fortransporting the inflation liquid may disturb the steady flow of theinflation liquid, thereby hindering efficient balloon inflation anddeflation. If the balloon inflation and deflation are prolongedsubstantially, the condition may result in an inadvertent, prolongedblockage of the artery, possibly causing harm to the patient.

Thus, a prepping procedure to remove air from the catheter is requiredby physicians or nurses prior to insertion of the catheter into apatient's body. Prepping a balloon dilatation catheter may typicallyinvolve removing the air from the catheter by pulling a vacuum on theproximal end of the catheter or injecting a liquid into the balloon androtating the catheter vertically so as to allow air in the catheter toexit through an opening at a proximal end portion. These methods ofremoving air, however, generally involve a number of cumbersomeprocesses and often are ineffective in completely removing the air fromthe catheter.

As a prepping procedure for removing air from a balloon dilatationcatheter, a catheter having a small opening at the distal tip of theinflatable balloon has been proposed. The opening allows the air trappedinside the balloon to exit through the opening as the catheter isprepped outside of the patient prior to insertion. However, the openingremains open even during the inflation procedure inside the patient,permitting a small amount of the inflation liquid to “weep” through theopening. This weeping requires a continuous injection of inflationliquid in order to compensate for the leaked inflation liquid andmaintain the dilation pressure.

SUMMARY OF THE INVENTION

Therefore, an embodiment of the invention relates to a balloon dilationcatheter that addresses the above-mentioned problems by providing amechanism which may selectively allow removal of the air trapped insidethe catheter without losing any inflation liquid. While the presentinvention will be described in connection with a balloon dilationcatheter, the invention may be applied to any other types of cathetersor devices that may require selective removal of air or gas, such as,for example, fluid injection catheters or drug dispensing devices. Theinvention may also be applied to numerous other catheters and devicesutilizing the balloon expansion mechanism, such as, for example, stentplacement/deployment catheters, dilatation-ureteral balloon catheters,nephrostomy balloon catheters, or latex balloon occlusion catheters, orother suitable medical devices that require a sealing process, such as,for example, a drug dispensing device for sealing a drug delivery pathafter dispensing a drug.

To attain the advantages and in accordance with the purpose of theinvention, as embodied and broadly described herein, one aspect of theinvention may provide a balloon assembly for a medical device,comprising an inflatable balloon, a fluid port in fluid communicationwith the inflatable balloon to supply inflation liquid to the inflatableballoon, an opening for permitting gas to exit the inflatable balloon,and an expandable material having a first configuration configured topermit gas to exit through the opening and a second configurationconfigured to retain inflation liquid in the inflatable balloon. Theopening may be located at a distal-most end of the inflatable balloon.The opening may be formed by a hollow tube extending from the inflatableballoon.

In another aspect of the invention, the expandable material may includea liquid-activatable material configured to close the opening uponcontact with inflation liquid. The expandable material may be configuredto close the opening after substantially all of the gas is removed fromthe inflatable balloon through the opening. The expandable material mayhave a material characteristic of expanding in volume from the firstconfiguration to the second configuration upon contact with inflationliquid. The expandable material may also be configured to expand fromthe first configuration to the second configuration in response tocontact with a bonding agent or catalyst of an inflation liquid. Priorto the contact with inflation liquid, the expandable material may remainin the first configuration without interfering with the passage of gasthrough the opening. The expandable material may be spaced from theopening in the first configuration, so that, prior to contact withinflation liquid, the material may not block the opening, but aftercontact with inflation liquid, the material may expand to the secondconfiguration and substantially close the opening.

In still another aspect of the invention, the expandable material mayinclude an occlusive material. The occlusive material may include aplurality of beads, which may be interconnected.

According to another aspect of the invention, the expandable materialmay be on an inside surface of the hollow tube. Prior to contact withinflation liquid, the material may remain in the first configuration andmay not block the opening. After contact with inflation liquid, however,the material may expand to the second configuration and substantiallyclose the opening. In an aspect, the expandable material may be coatedon the inside surface of the hollow tube.

In still another aspect of the invention, the expandable material mayinclude a hydrophilic material placed proximate the opening. Theexpandable material may be disposed in the form selected from the groupconsisting of particles, coating, porous matrix, fiber bundles, tubularbed, and any combination thereof.

In yet still another aspect of the invention, the expandable materialmay be selected from a group consisting of: super absorbent polymers;hydrogel polymers; water-swellable polymers; hydrocolloids;hydrocolloids having polymer compositions of substantiallywater-insoluble, slightly cross-linked, partially neutralized polymersprepared from unsaturated polymerizable acid group-containing monomersand cross-linking agents; polymer materials that have undergone across-linking process; polyacrylates; PEG; polysaccharides; starch orcellulose; generally carboxyl containing polymers; hydrolyzates ofstarch-acrylonitrile graft copolymers; partially neutralized products ofstarch-acrylic acid or polyvinyl alcohol graft copolymers;saponification products of vinyl acetate acrylic ester copolymers;derivatives of copolymers of isobutylene and maleic anhydride;hydrolyzates of acrylonitrile copolymers; cross-linked products ofhydrolyzates of acrylonitrile copolymers; cross-linked carboxymethylcellulose; polyaspartate hydrolyzates of acrylamide copolymers;cross-linked products of hydrolyzates of acrylamide copolymers;partially neutralized products of polyacrylic acids; cross-linkedproducts of partially neutralized polyacrylic acids; natural non-ionicpolymers; carraggeenan; xanthan gum; gelatin; agar; alginate; and anycombination thereof.

Another aspect of the invention may provide a balloon assembly for amedical device, comprising an inflatable balloon, a fluid port in fluidcommunication with the inflatable balloon to supply inflation liquid tothe inflatable balloon, an opening for permitting gas to exit theinflatable balloon, and a barrier material disposed on the opening andconfigured to allow gas to pass through the opening while preventingpassage of inflation liquid therethrough. In another aspect of theinvention, the barrier material may be selected from a group consistingof: papers, porous-type ceramics, fabrics, foams, filter materials, andany combination thereof.

Still another aspect of the invention may provide a dilation cathetercomprising an elongated tubular member having a distal end and aproximal end, a proximal handle proximate the proximal end of thetubular member, an inflatable balloon proximate the distal end of thetubular member with inflatable balloon being in fluid communication witha fluid port to supply inflation liquid to the inflatable balloon, theinflatable balloon including an opening for permitting gas to exit theinflatable balloon, and an expandable material having a firstconfiguration configured to permit gas to exit through the opening and asecond configuration configured to retain inflation liquid in theinflatable balloon.

In another aspect, the proximal handle may include a connection to asource of inflation liquid. The tubular member may include a lumen influid communication between the source of inflation liquid and the fluidport. Alternatively or additionally, the tubular member may define thefluid port.

In still yet another aspect of invention, a dilation catheter comprisingan elongated tubular member having a distal end and a proximal end, aproximal handle proximate the proximal end of the tubular member, aninflatable balloon proximate the distal end of the tubular member withinflatable balloon being in fluid communication with a fluid port tosupply inflation liquid to the inflatable balloon, the inflatableballoon including an opening for permitting gas to exit the inflatableballoon, and a barrier material disposed on the opening and configuredto allow gas to pass through the opening while preventing passage ofinflation liquid therethrough, may be provided. The barrier material maybe selected from a group consisting of: papers, porous-type ceramics,fabrics, foams, filter materials, and any combination thereof.

In accordance with another aspect of the invention, a method of removinggas from a medical device may be provided. The method may includeinjecting a liquid into the medical device so as to force the gas in themedical device to exit through an opening, and after the gas is removedfrom the medical device, substantially closing the opening. The medicaldevice may include an inflatable balloon, and the opening may be formedby the inflatable balloon.

In still another aspect, the method may also include orienting thedevice so that the opening may be located at a substantially highestelevation of the inflatable balloon. Injecting the liquid may force thegas in the medical device to exit through the opening.

According to yet still another aspect of the invention, the step ofsubstantially closing the opening may include contacting aliquid-activated valve with the liquid. The liquid-activated valve maybe positioned proximate the opening and may be configured tosubstantially close the opening upon contact with the liquid. Theliquid-activated valve may include a self-expandable material configuredto expand upon contact with the liquid.

In another aspect of the invention, the method may include deflating theinflatable balloon by withdrawing the liquid and/or inflating theinflatable balloon by injecting the liquid.

Still another aspect of the invention may provide a method of removinggas from a dilation catheter. The method may include providing adilation catheter comprising an elongated tubular member having a distalend and a proximal end, a proximal handle proximate the proximal end ofthe tubular member, and an inflatable balloon proximate the distal endof the tubular member with inflatable balloon being in fluidcommunication with a fluid port to supply inflation liquid to theinflatable balloon, the inflatable balloon including an opening forpermitting gas to exit the inflatable balloon. The method may alsoinclude injecting inflation liquid into the balloon through the fluidport so as to force the gas in the dilation catheter to exit through theopening, and after the gas is removed from the dilation catheter,substantially closing the opening.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention will be realized and attained bymeans of the elements and combinations particularly pointed out in theappended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of theinvention and together with the description, serve to explain theprinciples of the invention.

In the drawings:

FIG. 1 is a schematic side view of a balloon dilation catheter,according to an embodiment of the invention;

FIG. 2 is a cross-sectional view of the inflatable balloon of theballoon dilation catheter shown in FIG. 1, illustrating the balloon in adeflated state;

FIG. 3 is a frontal view taken from a plane (3-3) of FIG. 2, showing anair-ventilation opening;

FIG. 4A is a partial exploded cross-sectional view of the distal endportion of the inflatable balloon, according to another embodiment ofthe invention, with an air-ventilation opening in an open state;

FIG. 4B is a partial exploded cross-sectional view of the distal endportion of the inflatable balloon shown in FIG. 4A with theair-ventilation opening in a closed state;

FIG. 5 is a partial exploded cross-sectional view of the distal endportion of an inflatable balloon, according to still another embodimentof the invention; and

FIGS. 6-10 are schematic cross-sectional views of the inflatable balloonshown in FIG. 2, illustrating an exemplary method of prepping a balloondilation catheter, according to an embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the exemplary embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

According to an exemplary embodiment of the invention, FIG. 1illustrates a balloon dilation catheter 1 having an air-ventilationopening 39 used to remove air from the catheter 1, for example, during aprepping procedure performed prior to insertion of the catheter 1 into apatient's body. While the invention will be described in connection witha particular balloon dilation catheter, the invention may be applied to,or used in connection with, any other types of balloon dilationcatheters, numerous other catheters utilizing a balloon expansionmechanism, such as, for example, stent placement/deployment catheters,dilatation-ureteral balloon catheters, nephrostomy balloon catheters, orlatex balloon catheters (e.g., occlusion balloons of Boston ScientificCorporation), or other suitable medical devices that require a sealingprocess, such as, for example, drug dispensing devices for sealing adrug delivery path after dispensing a drug, or that require removal ofair or gas from the devices, such as, for example, fluid injectioncatheters or drug dispensing device.

As shown in FIG. 1, the balloon dilation catheter 1 may include anelongated flexible tubular member 20, a proximal handle assembly 10coupled to a proximal end of the tubular member 20, and an inflatableballoon 30 attached to the distal end portion of the tubular member 20.The catheter 1 may be used with a flexible guide member 25, such as, forexample, a wire, for guiding insertion of the catheter 1 through a bodylumen. The distal tip portion 40 of the catheter 1 may be tapered so asto facilitate the insertion of the catheter 1 through the body lumen.

The handle assembly 10 may include a T- or Y-connector 15 having a mainport 14 for receiving the guide member 25 and a side port 13 forconnecting to a source of pressurized inflation liquid (not shown). Theinflation liquid may include a saline solution, dye solution, water, orany other suitable liquid medium known in the art. In an embodiment, asyringe device (not shown) having a pressure gauge may be used to injectand retract the inflation liquid, while monitoring the balloon pressure.Any other device suitable for injecting inflation liquid may be used.

Each of the main port 14 and the side port 13 may include a suitableconnector 11, 12, such as a luer-type connector or threaded connector.The connector 11, 12 may also include a sealing member (not shown) toprevent any leakage from the catheter 1. The handle assembly 10 mayinclude a connecting member 19 that allows detachment of the connector15 and/or replacement of the connector 15 with any other suitableconnector, such as, for example, a connector having more than two ports.

The handle assembly 10 and the tubular member 20 may include a pluralityof lumens for separately accommodating the guide member 25 and theinflation liquid. In an exemplary embodiment, the tubular member 20 mayinclude a fluid lumen 31 (see FIG. 2) that is in fluid communicationwith the side port 13 of the handle assembly 10. The guide member 25 mayextend from the main port of the handle assembly 10, pass through alumen of the tubular member 20, preferably separate from the fluid lumen31, and extend to the distal tip portion 40.

As shown in FIGS. 2 and 3, the inflatable balloon 30 may be attached toor integrally formed with the tubular member 20. Alternatively, theinflatable balloon 30 may also be detachably coupled to the tubularmember 20. The tubular member 20 may include a fluid port 32, throughwhich the inflation liquid may be injected into the balloon 30. Theballoon 30 may be formed of any suitable material having a sufficienttensile strength to sustain a desired pressure in the balloon 30, whilemaintaining a relatively thin wall thickness 35 in order to have a lowdeflated profile of the balloon 30. Possible materials for the balloonmay include thermoplastic polymers, such as, for example, polyethyleneterephthalate (PET), polyurethanes, polyethylenes and ionomers,copolyesters, rubbers, polyamides, or any other suitable materials knownin the art.

At the distal end of the balloon 30, an opening 39 or slot may be formedfor use in, for example, ventilating air out of the balloon 30. In anexemplary embodiment shown in FIGS. 2 and 3, the opening 39 may beformed with a tubular member 37 (e.g. a capillary tube) extending fromthe inside of the balloon 30 to the outside. While the figure shows onlyone opening 39, the balloon 30 may include a plurality of openings orslots. The opening 39 may be positioned at the distal-most end of theballoon 30 (i.e., at the highest elevation when the balloon is orientedvertically), so as to allow all of the air forced to the top of theballoon 30 to be completely removed through the opening 39 when theinflation liquid fills up the balloon 30. Alternatively, an opening 39may be position at a location other than the distal-most end of theballoon 30.

According to an embodiment of the invention, the inflatable balloon 30may include a hydrophilic material 38 placed on, or in the vicinity of,the opening 39, as shown in FIGS. 2 and 4A-B, for example. The material38 may function as a liquid-activated sealing valve for selectivelypermitting the air to exit the balloon 30, while retaining the inflationliquid in the balloon 30. The hydrophilic material 38 may be placed ordeposited in the form of particles, coating, porous matrix, fiberbundles, tubular bed, or any other suitable means known in the art.Hydrophilic materials may have a unique material characteristic ofabsorbing moisture and self-expanding in volume after being exposed toan aqueous atmosphere. Owing to this moisture-sensitive expansioncharacteristic, the hydrophilic material 38 may be used to selectivelypermit removal of only the trapped air out of the balloon 30.

For example, as will be described later in further detail, the catheter1 may be aligned vertically with the opening 39 positioned at thehighest elevation. A suitable inflation liquid, injected through theside port 13, may pass through the fluid lumen 31 and into the balloon30. The injection of the inflation liquid may force the air in the lumen31 and the balloon 30 to be collected at the distal portion of theballoon 30. As the injection of the inflation liquid continues, the airtrapped at the distal portion of the balloon 30 may then be forced outof the balloon 30 via the opening 39. When the inflation liquid levelreaches the location where the hydrophilic material 38 may be placed,which occurs preferably after all or substantially all of the air in theballoon 30 has been removed, the inflation liquid may be brought intocontact with the hydrophilic material 38, causing expansion of thematerial 38, preferably rapid or immediate expansion, and substantiallysealing the opening 39. At this condition, the hydrophilic material 38may expand, effectively occluding the opening 39 without requiring anyadditional bonding agent. Before the initial contact between theinflation liquid and the hydrophilic material 38, the hydrophilicmaterial 38 may remain in its original shape and size withoutinterfering with the passage of air through the opening 39.

Suitable materials having the liquid-activatable expansion capabilityinclude, but are not limited to the following: super absorbent polymers;hydrogel polymers; water-swellable polymers; hydrocolloids that arepolymer compositions of substantially water-insoluble, slightlycross-linked, partially neutralized polymers prepared from unsaturatedpolymerizable acid group-containing monomers and cross-linking agents;or any other materials known in the art.

In particular, the polymer materials that have undergone a cross-linkingprocess may have a relatively high gel volume and a relatively high gelstrength upon contacting a liquid. The degree of cross-linking inhydrogel (or hydrophilic) and hydrogel-forming materials may be animportant factor in establishing characteristics of liquid absorbinghydrogels, i.e., absorbent capacity and gel strength. Absorbent capacityof “gel volume” is a measure of the amount of water or body liquid thata given amount of hydrogel-forming material will absorb. Gel strengthrelates to the tendency of the hydrogel formed from such material todeform or flow under an applied stress. Since the materials havedifferent expansion rates, the time it takes to expand and completelyocclude the opening 39 may be controlled by properly selecting asuitable material.

Suitable polymers may include: polyacrylates; PEG; polysaccharides;starch or cellulose; generally carboxyl containing polymers; and anyother suitable polymers known in the art. Examples ofcarboxyl-containing water absorbent polymers may include, but not belimited to: hydrolyzates of starch-acrylonitrile graft copolymers;partially neutralized products of starch-acrylic acid or polyvinylalcohol graft copolymers; saponification products of vinyl acetateacrylic ester copolymers; derivatives of copolymers of isobutylene andmaleic anhydride; hydrolyzates of acrylonitrile copolymers; cross-linkedproducts of hydrolyzates of acrylonitrile copolymers; cross-linkedcarboxymethyl cellulose; polyaspartate hydrolyzates of acrylamidecopolymers; cross-linked products of hydrolyzates of acrylamidecopolymers; partially neutralized products of polyacrylic acids; andcross-linked products of partially neutralized polyacrylic acids.Alternatively or additionally, natural non-ionic polymers, such as, forexample, carraggeenan, xanthan gum, gelatin, agar, and alginate, mayalso be used.

In an exemplary embodiment, the hydrophilic material 38 may be mixedwith a suitable occlusive material, such as, for example, small beads,to facilitate the blockage of the opening 39. The small beads may bestrung onto a thread or may be interconnected to each other. In anexemplary embodiment, the material may be prepared in such a way thatthe expansion occurs only when the material is contacted with a specifictype of bonding agent or catalyst.

In an exemplary embodiment, such as the embodiment shown in FIG. 2, thehydrophilic material 38 may be placed on the outer surface of thetubular member 20 or on the inner surface of the balloon 30, preferablyat a location proximate the opening 39. The hydrophilic material 38 maybe separated from the opening 39 by a suitable distance. The distancemay be configured in such a way that, prior to the expansion, thehydrophilic material 38 may not interfere with the passage of airthrough the opening 39, but, upon contact with the inflation liquid, maysufficiently expand and occlude the opening 39.

FIGS. 4A and 4B show another exemplary embodiment of the invention. Inthis embodiment, the inside surface of the tubular member 37 may becoated or treated with the hydrophilic material 38′, as shown in FIG.4A. This embodiment may be used in combination with the hydrophilicmaterial 38 placed in the vicinity of the opening 39, as shown in FIG.2.

The principles of operation relating to the embodiment of FIGS. 4A and4B may be substantially the same as those described above with referenceto FIG. 2. For example, the air may be forced to the distal portion ofthe balloon 30 and vented out through the opening 39 when the inflationliquid is injection into the catheter 1. Until the inflation liquidreaches the opening 39, the hydrophilic material 38′ may remain in itsoriginal shape and size without interfering with the air flow though thetubular member 37. Once the inflation liquid reaches the tubular member37 and makes contact with the hydrophilic material 38′ inside the tube37, the material 38′ then rapidly and/or substantially immediatelyabsorbs the inflation liquid and expands to sealingly close the opening39, as shown in FIG. 4B.

FIG. 5 shows still another exemplary embodiment of the invention. Inthis exemplary embodiment, the opening 39 may be provided with a one-wayvalve 38″, which may selectively allow only the air to pass through thevalve 38″. For example, the valve 38″ may include a suitable barriermaterial that may allow the air to pass through (indicated by dottedarrow 58), while preventing passage of water or vapor (indicated bysolid arrow 52). The barrier materials may include, for example, TYVEK®papers (manufactured by Dupont), Porex or porous-type ceramics,GORE-TEX® fabrics, foam or filter material having controlled pore size,or any suitable materials known in the art. The barrier material mayalso include a hydrophilic material that, upon contact with liquid, mayexpand and seal the opening 39. In various exemplary embodiments, thehydrophilic material may be coated on or embedded with the barriermaterial.

A method of operating the catheter 1, according to an embodiment of theinvention, will be described in detail with reference to FIGS. 6 through10. While operational aspects of the invention will be described with anexemplary embodiment of the inflatable balloon shown in FIGS. 2 and 3,and in connection with a particular balloon dilation catheter, theinvention may be applied to other suitable medical procedures, or usedin connection with any other suitable medical devices, without departingfrom the scope of the invention. For example, the invention may be usedto control bulking of a detachable balloon for use in an embolic device(e.g., when the embolic device is no longer needed) or as a sealingvalve. Furthermore, the invention may be applied to other variousmedical devices, such as, for example, numerous other cathetersutilizing the balloon expansion mechanism, such as, for example, stentplacement/deployment catheters, dilatation-ureteral balloon catheters,nephrostomy balloon catheters, or latex balloon occlusion catheters, orother suitable medical devices that require a sealing process, such as,for example, a drug dispensing device for sealing a drug delivery pathafter dispensing a drug, or that require removal of air or gas from thedevices, such as, for example, fluid injection catheters or drugdispensing device.

FIGS. 6-10 show schematic cross-sectional views of the inflatableballoon 30 in a vertically oriented position, illustrating variousstages of an exemplary prepping procedure performed prior to insertionof catheter 1 into a patient's body. As shown in FIG. 6, injection ofthe inflation liquid 55 through the fluid lumen 31 and into the balloon30 may force the air in the lumen 31 and the balloon 30 to the distalportion of the balloon 30. The flow paths of the air and the inflationliquid 55 are indicated with dotted arrows 58 and solid arrows 52,respectively. Injection of the inflation liquid 55 into the balloon 30may force the air to be vented out of the balloon 30 via the opening 39formed at the distal-most end of the balloon 30. At this condition, asshown in FIG. 7, the injection of the inflation liquid 55 may cause theballoon 30 to inflate. The degree of inflation and the balloon pressuremay be controlled by controlling the flow rate and the amount of theinflation liquid 55 injected into the balloon 30. As more inflationliquid 55 passes into the balloon 30 and more air is vented out of theballoon 30, the liquid level in the balloon 30 may rise to a level wherethe liquid 55 contacts the hydrophilic material 38. The hydrophilicmaterial 38, upon contact with the inflation liquid 55, may absorb aportion of the inflation liquid 55 and may expand to substantially sealthe opening 39, as shown in FIG. 8. At this point, the air thatpreviously existed in the balloon 30 and the lumen 31 has already beenremoved from the catheter 1.

As shown in FIG. 9, after the air is removed from the balloon 30 and theopening 39 is substantially sealed, the balloon 30 may be deflated bywithdrawing the inflation liquid 55 back through the fluid port 32. Asuitable deflation device, a syringe device or a suction device,connected to the side port 13 of the handle assembly 10 may be used todeflate the balloon 30. In an exemplary embodiment, the same device usedto inflate the balloon 30 may be used.

The balloon 30 and the fluid lumen 31 may then be drawn into a vacuumwith no air present or they may include only a residual amount ofinflation liquid 55 used to prep the catheter, as shown in FIG. 10. Withthis condition of the balloon 30, the balloon dilation catheter 1 may beinserted into a patient's body for performing the intended procedure.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

1. A balloon assembly for a medical device, comprising: an inflatableballoon; a fluid port in fluid communication with the inflatable balloonto supply inflation liquid to the inflatable balloon; an opening forpermitting gas to exit the inflatable balloon; and an expandablematerial having a first configuration configured to permit gas to exitthrough the opening and a second configuration configured to retaininflation liquid in the inflatable balloon. 2-95. (canceled)